SMAD1 and glioblastoma: Survival analysis based on the cutoff at a median level of Smad1 in GBM indicated that higher Smad1 was correlated with poorer clinical prognosis (Figure 1L, Log‐rank χ2 = 5.019, p = 0.025) regardless of age or sex (Table S1 and Supplemental Data 1, Supporting Information).